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Y. OGAWA.

FORCED DRAFT DEVICE FOR FURNACES.

APPLICATION FILED JAN- 23. 1917- 1,322,262. Patented Nov. 18, 1919.

2 SHEETS-SHEET l.

Y. OGAWA.

FORCED DRAFT DEVICE FOR FURNACES.

APPLICATION HLED 1AN.23.117-

1,322,262. Patented NOV. 18, 1919.

2 SHEEISSHEEI 2.

Jay/2 6 2 B /Z1 25 g 27 1 W A 29 YEITARO OGAWA, OF KUSUNOKI MAUI-II, KOBE, JAPAN.

FORCED-DRAFT DEVICE FOR FURNACES.

Specification of Letters Patent.

Patented Nov. 18, 1 919.

' Application filed January 23, 1917. Serial No. 144,090.

To all whom it may concern:

Be it known that I, YErrAno OGAWA, a subject of Japan, residing at No. 4, lot No. 79, Shichi-chome, Kusunoki Machi, Kobe, Japan, engineer, have invented new and use ful Improvements in Forced-Draft Devices for Furnaces, of whichthe following is a specification.

This invention relates to a forced draft device for furnaces, and consists in the provision in the uptake or smoke chamber of a large number of air tubes through which the forced air passes to the furnace, being heated on the way by the hot waste gas which heats the said air tubes; in the provision of separate air passages to each furnace, the said air passage being provided with air valves which can be opened or closed; and in the provision of mechanism for opening or closing the said air valves. The object of this invention is to obtain an efficient and durable air heating device, to insure complete combustion by sending to the firegrate air heated by said device, and to facilitate the handling of the furnaces by providing means to open or close any desired furnace without interfering with the other furnaces.

Figure 1 shows an example of application of this invention to a multitubular cylindrical boiler, and is a front elevation thereof, showing a section on the line I-I of Fig. 2.

Fig. 2 is a side elevation showing a section on the line 11-11 of Fig. 1.

Fig. 3 is a sectional plan view on the line III-III of Fig. 1.

Fig. 4 is a sectional front view, enlarged, on the line IV-IV of Fig. 2.

Fig. 5 is a front view, enlarged, of a cleaning plate, and

Fig. 6 is a side view of the same.

Fig. 7 is a front view showing a modified arrangement of air tubes, and

Fig. 8 is a plan View showing another modification of the arrangement of air tubes.

Fig. 9 is an enlarged detail view showing in front elevation, the furnace 0 shown in the receding views.

The same reference numbers refer to same or corresponding parts throughout all the figures. V

The accompanying drawings show this'invention as applied to a multitubular cylindrical boiler furnished with three furnaces, and may be described as follows:.

The waste gas that comes from the smoke tubes collects, as in the case of ordinary boilers, in the smoke box 1, Fig. 2, and escapes through the funnel 2. At a suitable place in this uptake or smoke box is provided a forced air chamber 4 to receive the forced alr which comes from the blower through the passage 3. On both sides of this air chamber 4 are provided closed air passages 5, 5 which communicate respectively with furnaces A and B. In the central part of the boiler are provided two more closed air passages 6, 6' which lead respectively from the air passages 5, 5 and terminate in the furnace C. The furnaces are arranged at the sides and central portion of the bottom of the apparatus and the air passages 5 and 5 constitute outer side passages and communicate with the side furnaces at the outer sides thereof, while the inner passages 6 and 6' are connected with the central furnace at opposite sides of the same. Between the tube plates 7 of the forced air chamber 4 and the tube plates 8 at the upper part of the air passages 5, 5 are provided a large number of air tubes 9. When the air is forced through the air passage 3, it will at the forced air chamber 4 be divided into two currents, one going to the air passage 5 through the air tubes 9 which connect the forced air chamber with the air passage 5, and the other current going to the air passage 5 through the air tubes 9 which connect the same forced air chamber with the air passage 5'. The air while passing the air tubes 9 will be heated, as the tubes are heated by the very hot waste gas which ascends from the furnaces through the smoke box. Part of the air thus heated will then pass down the air passages 5 and 5 to the furnaces A and B respectively. Part of the heated air, however, will be intercepted by partitions 10, 10 and will descend the central air passages 6, 6 to the furnace C.

The outer side passages 5 and 5 and the pair of inner passages Gand 6 are fitted respectively with air valves 11, 11, 12 and 12 and either of the air valves 11 and 11 orthe pair of air valves 12 and 12' may be operated independently by the means hereinafter described for controlling the passage of heated air to the side and central furnaces.

An example of the valve controlling device is shown in Fig. 4. Commencing with the furnace A, an arm 15 of a shaft 14 is connected by means of a connecting rod 1.7

with an arm 19 of a shaft 18; a bevel wheel 20 fixed to the said shaft 18 engages with a bevel wheel 22 fixed at one end of a shaft 21; and a bevel wheel 23 at the other end of the said shaft 21 engages wit-ha bevel wheel 25 of a shaft 21 of an air valve 11. The device for opening or closing the air valve for the furnace B is nearly the same as that for the furnace A, and therefore description thereof is here omitted. From the above arrangement it will be seen that by turning the shaft 11 of the furnace A, B, or C, the air valves 11, or 11, or 12 and 12 can be opened or closed as desired. The air passages 6 and G are fitted respectively with air valves 12 and 12 such valves being operated to control the passage of air through said passages in a maimer similar to the valves 7 and 11. As shown in Fig. 4 an arm 16 of a shaft 1 1 is connected with an arm 28 fixed to a shaft 27 of an air valve 12 by means of a connecting rod 26, and another arm 29 of the same shaft 27 is con nected with an arm 31 of a shaft 30 of an air valve 12 by means of a connecting rod 32. By turning the shaft 1 1 valves 12 and 12 are opened and closed simultaneously as will be understood. If the front end of the shaft 11 of each furnace be connected with a lever for fastening the firedoor of each furnace, the air valves can be opened or closed by motion of the said lever. For example, if it is desired to open the furnace A, and if the firedoor fastening lever 13 be turned toward the left, the shaft 14 will be turned, which will turn the shafts 18 and 2 1, and thus the air valve 11 will be closed, as is shown in the figure by dotted lines, and the draft for the furnace A will thus be temporarily intercepted. So with the case of the furnace C. If the firedoor fastening lever thereof be turned toward the left in order to open that firedoor, the valves 12, 12 will be closed and will intercept the draft which enters the said furnace.

The air tubes 9 are provided, as shown in Figs. 5 and 6, with a tube cleaning plate 33 which has a large number of holes corresponding to the air tubes 9. This plate has a hole in which screw thread is cut and through this hole passes a screw rod 35. Thus by turning the handle 36 of the screw rod 35 one way or the other, the tube cleaning plate may be made to move backward or forward, thus cleaning the tubes from the soot adherin on their outer surfaces.

The Fig. I shows a modification of the disposition of the air tubes, in which the forced air is made first to pass, from the forced air chamber 41, through a set of air tubes 9 in the direction of the arrows, then through another set of air tubes 9, and lastly through a third set of air tubes 9, after which it passes to the air passage 5 and then to the furnaces- The Fig. 8 shows another modification in which air tubes are fixed parallel to the axis of the boiler. In this the forced air is made to pass, from the forced air chamber 4, through air tubes 9, in the direction of the arrows, then through air tubes 9 in the direction of the arrows, and then to the air passage. In these modifications the forced air is made to pass successively through different air tubes, and thus it is more eificiently heated. v

To use this invention with a closed stokehold, the draft forced into the stokehold from the blower, is sent to forced air chambers of the furnaces through a suitable opening, and is applied to the furnaces in the same manner as described in the above example. It goes without saying that this invention can be used also with water tube boilers.

According to my invention forced air is made to pass through a large number of air tubes fitted in the uptake or smoke box, said tubes being heated from outside by the waste gas which ascends from the furnaces through the said uptake or smoke box. The air is thus efliciently heated while passing through the air tubes, and passes into the furnaces through air passages provided separately for each furnace. Thus my invention has the following advantages over furnaces hitherto in use which has a common passage for all the furnaces :-that draft for each furnace can be regulated and thus fuel can be completely burnt, and that the firedoor of any one desired furnace can be opened by temporarily intercepting the draft for that furnace.

I am aware that there is an air heating device in which air is heated by coming into contact with smoke tubes through which waste gas from furnaces ascends. However, when this device is used for a long time, the smoke tubes become choked with soot, which not only interfere with the free passage of smoke but injures the tubes. Now, according to my invention, the waste gas is made to heat air tubes from outside, and as the air tubes are provided with a cleaning plate, they can be cleaned of soot which adheres to them by operating this plate now and then, with hand or by any other suitable means, and be kept always clean; Thus not only is the passage of the smoke not intercepted, but the tubes will always remain good conductors of heat, and their life too will be very long. 1

Having thus described my invention, what I claim and desire to secure by Letters Patcut is 1. In combination with central and side furnaces having a common smoke box, a forced air chamber located centrally in the upper portion of the smoke box, air tubes arranged in sets at opposite sides of the forced air chamber, and communicating at their inner ends with the same, outer side passages connected with the side furnaces and extending upwardly therefrom to and communicating with the outer ends of the said air tubes, a pair of inner tubes connected with the central furnace and extending upwardly therefrom and communicating with the upper portions of the side passages, and means for controlling the passage of air through the inner and side passages.

2. In combination with central and side furnaces having a common smoke box, a forced air chamber located centrally in the upper portion of the smoke box, air tubes arranged in sets at opposite sides of the forced air chamber, and communicating at their inner ends with the same, outer side passages connected with the side furnaces and extending upwardly therefrom to and communicating with the outer ends of the said air tubes, 21- pair of inner tubes connected with the central furnace and extend ing upwardly therefrom and communicating with the upper portions of the side passages, bafile plates located at the upper portions of the side passages and arranged to deflect a portion of the air from the air tubes into the inner passages, and means for controlling the passage of air through the side and inner passages.

3. In combination with central and side furnaces having a common smoke box, a forced air chamber located centrally in the upper portion of the smoke box, air tubesarranged in sets at opposite sides of the forced air chamber, and communicating at their inner ends with the same, outer side passages connected with the side furnaces and extending upwardly therefrom to and communicating with the outer ends of the said air tubes, a pair of inner tubes connected with the central furnace and extending upwardly therefrom and communicating with the upper portions of the side passages, bafiie plates located at the upper portions of the side passages and arranged to deflect a portion of the air from the air tubes into the inner passages, a pair of valves located in the inner passages, side valves located in the side passages, means for operating the valves in the inner passages simultaneously, and separate means for operating the valves in the side passages independently of each other and independently of the valves in the inner passages.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

YEITARO OGAWA. 

